The present invention relates to systems for simulating light conditions.
Humans and other animals live under conditions of natural illumination. Natural light is a dynamic light condition that exhibits daily and seasonal changes in intensity, color spectrum, and duration. Many species of plants, animals, and microorganisms have biological processes that are attuned to environmental illumination patterns and lighting conditions. It is well known that changes in these illumination patterns and lighting conditions can have significant physiological and behavioral effects. For instance, the seasonal growth and reproduction cycles of many plant species are tied to seasonal changes in natural light conditions. Some plants, for example, that always flower at a specific time of year are sensitive to the photoperiod, the relative lengths of night and day, and use this to determine when to flower.
Changes in illumination patterns and lighting conditions can also have dramatic effects on the physiology, psychology, and mood of humans. For instance, in certain geographical areas, an estimated 20% of the human population may be affected by winter depression, or seasonal affective disorder (xe2x80x9cSADxe2x80x9d), a condition associated with reduced exposure to natural light during the winter season. Symptoms of this disorder can include fatigue, depression, and changes in appetite and sleep patterns. Recent research has revealed that extended exposure to bright light can help alleviate many of the symptoms of SAD in some patients.
Most living creatures, including humans, have an internal biological clock that controls many life functions in rhythmic patterns, which include 24-hour patterns known as circadian rhythms. These biological rhythms help to regulate a wide variety of biological processes. A number of maladies, such as jet lag, certain mood disorders, and sleep disorders, are associated with a disruption in these intrinsic rhythms. Since environmental illumination patterns are believed to play a role in regulating the internal clock of humans and other organisms, various forms of light therapy have been used to treat many of these conditions.
Many of the artificial indoor lighting conditions that are commonly encountered in modern society are arbitrary and bear little relationship to natural light conditions. It is believed that certain artificial lighting conditions may have an adverse effect on the natural biological rhythms that influence human behavior. These effects are likely to be particularly pronounced when individuals spend prolonged periods of time in windowless interiors where there is little or no exposure to natural light conditions. Although little is presently known about the impact that arbitrary artificial lighting conditions may have on long term human performance and productivity, in many instances human health, comfort, and psychological well-being may well be enhanced by providing lighting conditions that more closely mimic the patterns, intensity, and spectrum of natural light.
Previous attempts have been made to develop illumination devices that simulate natural light conditions. For example, Maute et al. in U.S. Pat. No. 4,074,124 describe an illumination apparatus that uses an artificial light source concealed by shutters. As the shutters gradually open they expose increasingly larger portions of the light source, thereby simulating dawn and morning light conditions. Conversely, as the shutters close, they gradually conceal increasingly larger portions of the light source, thereby simulating afternoon and dusk conditions. Daffer et al. in U.S. Pat. No. 5,645,578 disclose a sauna bed that is capable of simulating the intensity and direction of natural light at mid-day. Colored lights and a strobe light located in the hood of the sauna bed provide alternative lighting regimes. Terman et al. in U.S. Pat. Nos. 5,343,121 and 5,589,741 describe a system that produces variable intensity illumination cycles that can be programmed to correspond to naturally occurring illumination cycles. Gart et al. in U.S. Pat. No. 5,849,027 disclose an apparatus that delivers optical light energy for the therapeutic treatment of various dermatological and internal diseases. The device includes lenses, filters, fiber optics, and power control elements to regulate the intensity and frequency of the light energy being applied to the patient. Recently, Dial in U.S. Pat. No. 5,824,024 described a compact illumination apparatus for treating light deficiency and mood disorders that utilizes neon fixtures. The apparatus employs multiple colored tubes, dimmers, and timers to simulate natural lighting conditions, such as sunrise and sunset.
Illumination devices that provide controlled exposure to bright light or that attempt to simulate natural light conditions have been used to treat a variety of physical and psychological disorders, including SAD, jet lag, sleep disorders, circadian abnormalities, and the like. Such devices have also been used in research laboratories to study the effects of environmental illumination patterns in a wide range fields, including animal behavior and plant physiology.
The present invention features an apparatus and method for generating artificial light that mimics a dynamic light condition. The apparatus includes (a) multiple illumination sources that emit light of different wavelengths; (b) a means for detecting the spectral characteristics of the sum of the emitted light and transmitting this information to a computer; and (c) a means for sending control signals from the computer to the illumination sources to control the intensity of illumination from a plurality of the illumination sources to alter the spectral characteristics of the emitted light so that the light mimics the desired dynamic light condition over time. In one embodiment, the dynamic light condition that the apparatus mimics is natural light.
In a preferred embodiment, the apparatus includes sources of white, blue, yellow, and red light. It also includes an electronic driver capable of translating low-level control signals generated by standard computer peripherals into high-power signals for directly controlling the illumination sources. The means for detecting spectral characteristics of the emitted light includes a collection of photocells and filters. The computer is preferably a stand-alone personal computer.
The invention can be used to treat a variety of light-sensitive psychological disorders, including SAD, depression, sleep disorders, jet lag, chronobiological disorders, and circadian rhythm disorders. It can also be used to alter natural animal behavior, including facilitating or inhibiting seasonal behaviors such as mating. In another embodiment, the invention can be used to facilitate, inhibit or otherwise modify cycles of plant growth, flowering, or fruit production.
The present invention is able to simulate all of the gradual changes in intensity, spectrum, and duration exhibited by natural light at different times of the day and year, and at different locations on the planet, thereby mimicking the dynamic qualities of natural light. It has a wide range of potential applications, including use in the work-place, research situations, hospitals, industry, and in the home.
Other features and advantages of the invention will be apparent from the following description of the preferred embodiments thereof and from the claims.